This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-342819, filed Nov. 8, 2001, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a contents distributing system and method for a memory card on which contents such as music data are recorded, and in particular, to a memory card having a security function and a contents distributing system and method.
2. Description of the Related Art
The use of a memory card for enjoying digital contents such as music or games has been started as a purchasing method called a xe2x80x9creproduction limitedxe2x80x9d service in which the period or number of possible reproductions is limited to reduce set prices. Thus, manufacture costs and thus contents prices have decreased compared to package media such as CDs (Compact Discs), which are purchased and owned by users so that the contents can be reproduced at any time and any number of times.
However, to further reduce the contents prices, efforts must be made to limit the period of time over which contents can be reproduced for enjoyment or the number of reproductions. With the current memory card, a user obtains data on the number of times of use upon purchasing contents so that the number of times of use can be counted at the start or end of reproduction. However, the length of reproduction time may vary with the content or reproduction may be stopped before the content ends. Consequently, the count may be unfair, and thus this method was difficult to facilitate. That is, it is difficult to determine when to count the number of reproductions. For example, if this number is counted at the start of each song, a counting operation may be performed during a head search. Further, if the number is counted at the end of each song, the user may stop reproduction before the song ends and then listen to it from the beginning again. This enables the user to avoid being counted up. Furthermore, even if the number is counted in the middle of each song, the user can similarly avoid being counted up by stopping reproduction immediately before the count-up operation. To prevent this situation to achieve fairness, the amount of data reproduced must be counted. However, it was technically difficult to carry out this counting with the current memory card. That is, the memory card could not be provided with a function of keeping up with a reproduction speed to count the amount of data reproduced.
That is, the counting operation cannot be attained without relying on a count processing function of external equipment. Accordingly, such external equipment may modified to cheat at the count. Further, the memory card can be incorporated into various types of reproducing equipment so as to reproduce contents. To allow the amount of data reproduced to be counted, all of the various pieces of external equipment must be provided with a function of counting this amount. This is cumbersome, and particularly in the case of portable equipment, may impair its characteristics of being compact and portable. Further, if only some pieces of external equipment have a count function, data is reproduced from the memory card using only these pieces of equipment. Consequently, reproduction means for the memory card is limited.
SD (Security Digital) cards and other memory cards having security functions store encrypted contents data and decryption key data used to decrypt the contents data, and use both data to reproduce the contents while decrypting the data. A serial number specific to each memory card is checked, and on the basis of this serial number, a decryption key is made and transmitted. Accordingly, even if all of the contents data and decryption key are copied to another memory card, the data cannot be decrypted. The contents data can be copied to another memory card, but if they are actually copied, information is recorded in the decryption key of the source memory card, indicating that the contents data has been copied to the different memory card. Thus, reproduction cannot be achieved using this memory card. That is, although the contents can be moved from one memory medium to another, they can be used by only one memory medium which has been purchased by the user. Further, if the contents are reproduced, the type of reproducing equipment is checked so that the data is sent out only to equipment having a registered security function. This prevents the contents from being illegally copied. Memory cards having such security functions constitute systems that can prevent the contents from being illegally copied.
Now, with reference to FIG. 16, description will be given of a process of writing contents to a conventional SD card. A SD card 200 is connected to a contents vending machine 201. The SD card 200 has a card interface controller 202, a memory core 203, a protect memory core 204, and a key information recording section 205. The contents vending machine 201 has a contents recording section 206 and an encrypting section 207. Then, a user inputs a content write request 208 to the contents vending machine 201. In response to the content write request 208, the contents vending machine 201 outputs a key request to the card interface controller 202 of the memory card 200. Then, upon receiving the key request, the card interface controller 202 outputs a request to the key information recording section 205. Then, the key information recording section 205 outputs key information to the card interface controller 202. Subsequently, the card interface controller 202 outputs the key information to the encrypting section 207.
Next, the encrypting section 207 outputs a corresponding decryption key and encrypted content to the card interface controller 202. Then, the card interface controller 202 outputs the decryption key to the protect memory core 204 and the encrypted content to the memory core 203. The content is then written to the SD memory card 200.
In this case, the decryption key data is organized as shown in FIG. 17. A content name 209 specifying decryption data 210 is recorded as a part of the decryption key data. Furthermore, copy status data 211 is recorded as a part of the decryption key data. The copy status data is recorded as xe2x80x9c1xe2x80x9d if, for example, the content specified by the content name has already been copied to another SD card. In this case, this SD card is set so that this content cannot be reproduced. This is to prevent unlimited illegal copying. On the other hand, xe2x80x9c0xe2x80x9d is recorded if the content has not been copied to any other SD cards. Thus, the SD card is set so that this content can be reproduced providing that the other conditions are met. Furthermore, count data 217 of possible reproductions remaining is recorded in the decrypting data.
Now, with reference to FIG. 18, description will be given of a conventional counting method used to reproduce data. In FIG. 18, the SD card is assumed to store encrypted data, decryption key data used to decrypt the encrypted data, and count data accompanying the decryption key data and indicating the counted number of reproductions remaining. The encrypted data contains, for each of the contents, a file name and a pair of decryption key data and count data on the number of reproductions remaining. That is, the SD card stores as many these sets of data as the contents. The encrypted data, decryption key, and remaining reproduction number count data are stored in a nonvolatile memory. An SD memory reproducing device 212 has a decrypting section 213 and a content output section 214. The SD memory reproducing device 212 further comprises a counter 216. The counter 216 receives the count data of the number of reproductions remaining attached to the decryption key through the decryption to make an initial setting of the number of reproductions remaining, count the number of plays such as music plays and inform an information of the number of possible reproductions still remaining to the decrypting device. The decrypting device no longer decrypts when the number of reproductions remaining reaches zero.
First, a request 215 for a read of a specific content is externally input to the SD memory reproducing device 212. Then, the SD memory reproducing device 212 outputs a key request to the card interface controller 202. Then, the key information recording section 205 outputs key information to the card interface controller 202. Then, the card interface controller 202 outputs the key information to the decrypting section 213. Furthermore, the card interface controller 202 outputs a decryption key request to the protect memory core 204. Then, the protect memory core 204 outputs a decryption key and a count data of the number of reproductions remaining to the card interface controller 202. Then, the card interface controller 202 outputs the decryption key and a count data of the number of reproductions remaining to the decrypting section 213. The count data of the number of reproductions remaining is set in a counter of the reproducing device.
Next, the SD reproducing device 212 outputs a content request to the card interface controller 202. Then, the card interface controller 202 outputs the content request to the memory core 203. Then, the memory core 203 outputs a corresponding encrypted content to the card interface controller 202. Then, the card interface controller 202 outputs the encrypted content to the decrypting section 213.
Thus, on the basis of the input key information, the decrypting section 213 uses the decryption key to decrypt and output the encrypted content to the user via the content output section 214. That is, the decryption key data from the SD memory card is transmitted to the decoder in the external equipment. The decrypted data is sequentially reproduced in the external equipment. The external equipment converts the transmitted data into music, game software, or book data to entertain the equipment user. The count value of the counter of the reproducing device is decremented by one each start or end of one tune or one game. The count value data of the counter is transferred to the SD card and overwritten and stored in a file of the count data of the number of reproductions remaining at the time when another tune or game is selected.
Such a method of limiting the number of reproductions is described in xe2x80x9cNikkei Electronics No. 738, pp. 94 to 98; issued on Mar. 8, 1999xe2x80x9d. Further, a method of limiting the number of reproductions and thus a possible reproduction period or other methods are described in Jpn. Pat. Appln. KOKAI Publication Nos. 2001-125961 and 2001-67794. Jpn. Pat. Appln. KOKAI Publication No. 2000-347696 and other documents describe methods of incrementing the number of reproductions after a specified period of reproduction time has elapsed. Further, Jpn. Pat. Appln. KOKAI Publication No. 2000-357371 describes a method of limiting the number of reproductions in an SD card. Furthermore, Jpn. Pat. Appln. KOKAI Publication No. 2000-148945 and other documents describe a technique of automatically removing unwanted information in an IC card to effectively utilize memory resources.
These conventional memory cards create the following problems:
A problem with the conventional memory cards is that different contents require the respective data utilization styles. Since music data is utilized by sequentially reproducing provided data, no significant problems occur even if the number of reproductions remaining is decremented at the beginning of each song. However, listening to a song only for a short time before stopping playing it is also counted as one reproduction. Also disadvantageously, some users desire to listen to only the former half of a song. A more serious problem occurs with book data. Most readers do not repeat reading the same part of a long novel or the like but sequentially read it little by little. As a result, the number of reproductions increments each time the apparatus is powered off, though the user actually reads through this novel only once.
Under these circumstances, there has been a strong demand for a limit on the reproduction of contents based on the amount of data reproduced in order to achieve fairness. If a counter is provided to count the number of reproductions and if it is provided in a reproducing device, then all reproducing devices must be provided with counters. This is a burden on the reproducing devices. Furthermore, if a counter is provided in the memory card main body, it is large in size compared to the size of the memory card, thus preventing a reduction in the size of the memory card. Accordingly, a small-sized memory card has been desired for which high security is ensured.
According to an aspect of the invention, there is provided a memory card comprising an interface which receives an input content from external equipment and outputs a content to the external equipment; an interface driver which drives the interface; a card interface controller which receives an input signal from the interface driver and outputs a signal to the interface driver; a security processing section controlled by the card interface controller to supply an encryption key to the card interface controller upon a content reproduction request; a memory core interface controlled by the security processing section and the card interface controller and including a binary counter which counts one of the amount of content reproduced and the number of times of content reproduced, in response to a request for reproduction of a content, and a memory core to and from which a content is written, read, and deleted by the memory core interface and which records one of the amount of content reproduced and the number of times of content reproduced, if a request for reproduction of a content is input to the memory core, the memory core outputting the encrypted content to the memory core interface if the reproduction request does not cause one of the amount of possible content reproduction and the number of times of possible content reproduction to be exceeded.
According to another aspect of the invention, there is provided a memory card comprising an interface which receives an input content from external equipment and outputs a content to the external equipment and which receives an input content automatic deletion signal; an interface driver which drives the interface; a card interface controller which receives an input signal from the interface driver and outputs a signal to the interface driver; a security processing section controlled by the card interface controller to supply an encryption key to the card interface controller upon a content reproduction request; a memory core interface controlled by the security processing section and the card interface controller and including a binary counter which counts one of the amount of content reproduced and the number of times of content reproduced, in response to a request for reproduction of a content, the memory core interface outputting a request for deletion of an encrypted content and an encryption key if the content automatic deletion request is input to the memory core interface, and a memory core to and from which a content is written, read, and deleted by the memory core interface and which records one of the amount of content reproduced and the number of times of content reproduced, if a request for reproduction of a content is input to the memory core, the memory core outputting the encrypted content to the memory core interface if the reproduction request does not cause one of the amount of possible content reproduction and the number of times of possible content reproduction to be exceeded, the memory core deleting the encrypted content and the encryption key if the memory core receives a request for deletion of the encrypted content and the encryption key.
According to a further aspect of the invention, there is provided a contents distributing system comprising a request permission determining circuit which receive a content supply request from a user to determine whether or not to permit the request; a content supply circuit which receives a result of determination made by the request permission determining circuit to supply a content to a memory card, and an encryption key supply circuit which receives the result of determination made by the request permission determining circuit to supply a content-decrypting encryption key to the memory card.
According to a further aspect of the invention, there is provided a contents distributing system comprising a request permission determining circuit which receive a content-decrypting encryption key supply request from a user to determine whether or not to permit the request, and an encryption key supply circuit which receives a result of determination made by the request permission determining circuit to supply a content-decrypting encryption key with possible reproduction amount data to a memory card.
According to a further aspect of the invention, there is provided a contents distributing system comprising a circuit which receives a specification request and a possible reproduction amount request for a content downloaded by a user; a circuit which provides a supply price to the user on the basis of the specified content and the possible reproduction amount, and an encryption key supply circuit which receives a download confirmation instruction from the user to supply a decryption key with the possible reproduction amount data specified in a memory card.
According to a further aspect of the invention, there is provided a method of distributing contents comprising receiving a specification request and a possible reproduction amount request for a content downloaded by a user; providing a supply price to the user on the basis of the specified content and the possible reproduction amount, and receiving a download confirmation instruction from the user to supply a decryption key with the possible reproduction amount data specified in a memory card.